染料木素、芹菜素、槲皮素、芦丁和落新妇苷对高尿酸血症小鼠黄嘌呤氧化酶活性及血清尿酸水平的影响

目的探讨黄酮类化合物染料木素、芹菜素、槲皮素、芦丁和落新妇苷体外对黄嘌呤氧化酶活性的影响,对高尿酸血症小鼠血清和肝脏黄嘌呤氧化酶活性的影响,同时评价对小鼠血清尿酸水平的作用。方法采用改良的紫外分光光度法测定染料木素、芹菜素、槲皮素、芦丁和落新妇苷体外对黄嘌呤氧化酶的抑制作用;采用尿酸酶抑制剂氧嗪酸钾诱导小鼠高尿酸血症模型,以分光光度法研究对小鼠血清和肝脏黄嘌呤氧化酶活性的影响,以磷钨酸法测定对小鼠血清尿酸水平的作用。结果体外实验表明这些黄酮类化合物对黄嘌呤氧化酶活性无明显影响。然而,体内实验观察到能够明显升高或降低黄嘌呤氧化酶的活性,而且,血清尿酸水平与血清黄嘌呤氧化酶活性密切相关,与肝脏黄嘌呤氧化酶活性无明显关联。该研究表明用这些黄酮类化合物给药的小鼠血清尿酸水平都高于正常对照组。结论这5种黄酮类化合物不能够作为替代别嘌醇的药物用来降低血清尿酸水平。     

红茴香小分子化合物降尿酸活性及ADMET性质的分子对接

目的明确红茴香降尿酸的活性成分及作用机制。方法通过检索相关文献建立红茴香已知小分子化合物配体库,从蛋白PDB数据库获得黄嘌呤氧化酶相关蛋白(1N5X,1FIQ)作为筛选降尿酸药物靶点,用Discovery Studio 3. 0(DS)中Lib Dock对接模块虚拟筛选黄嘌呤氧化酶抑制剂,用ADMET模块对药代动力学性质进行预测。结果红茴香中的黄酮苷类成分包括槲皮素-4'-O-β-D-葡萄糖苷、槲皮苷、芹菜素-6-O-β-D-芦丁糖苷等,与1N5X,1FIQ具有较高的对接分数和较为适合的ADMET性质。结论红茴香中黄酮苷类通过抑制黄嘌呤氧化酶活性具有降尿酸活性,可为进一步研究开发降尿酸药物提供参考。     

痛风颗粒各部位对高尿酸血症大鼠尿酸和黄嘌呤氧化酶活性的影响

目的 通过观察痛风颗粒各部位对高尿酸血症大鼠血尿酸、尿尿酸、血黄嘌呤氧化酶活性和肝脏黄嘌呤氧化酶活性的影响,探讨其治疗痛风的物质基础和机制.方法 以腺嘌呤合乙胺丁醇法诱导大鼠高尿酸血症模型,分别用磷钨酸法和酶比色法检测尿酸和黄嘌呤氧化酶的含量.结果 黄酮类成分在降尿酸和抑制黄嘌呤氧化酶活性上均起主要作用;生物碱类成分对尿中尿酸的排泄和血清黄嘌呤氧化酶活性的抑制起较重要作用,有机酸类成分均未表现出明显作用;全方和有效部位组合有明显的降尿酸和抑制黄嘌呤氧化酶活性的作用.结论 黄酮类、生物碱和有机酸类有效部位组合后的药效与处方药一致,是该处方的有效部位群,对高尿酸血症模型大鼠表现出的降尿酸和抑制黄嘌呤氧化酶活性的作用最为显著.     

栀子苷对氧嗪酸钾盐致小鼠高尿酸血症的作用及其机制研究

目的探讨栀子苷对氧嗪酸钾盐致小鼠高尿酸血症的作用及其机制。方法连续7d灌胃给予氧嗪酸钾盐诱导小鼠高尿酸血症,对比各组血清尿酸水平和24h尿酸排泄量,检测肝脏黄嘌呤氧化酶（XOD）的活性和肾脏尿酸转运体（mURAT1、mGLUT9、mOAT1）的mRNA和蛋白表达水平。结果栀子苷可显著降低高尿酸血症小鼠血清尿酸水平并升高24h尿酸排泄量,同时可抑制肝脏XOD活性,调节肾脏尿酸转运体的表达。结论栀子苷对氧嗪酸钾盐致小鼠高尿酸血症具有明显的改善作用,其作用机制可能是通过抑制XOD活性和调节尿酸转运体的表达水平实现。     

黄酮类化合物对葡萄糖-6-磷酸脱氢酶缺乏者红细胞的体外氧化作用

目的:探讨黄酮类化合物对葡萄糖-6-磷酸脱氢酶(G6PD)缺乏者红细胞氧化还原状态的影响。方法:将低、中、高浓度的槲皮素、黄芩素、芹菜素、漆黄素、木犀草素、柚皮素、桑黄素、山奈酚、葛根素和芦丁分别与G6PD缺乏者及正常者红细胞在40%红细胞悬液和全血中进行体外孵育,测定红细胞还原性谷胱甘肽(GSH)和高铁血红蛋白(MetHb)的水平。结果:槲皮素、黄芩素、芹菜素、漆黄素、木犀草素、柚皮素、桑黄素、山奈酚具有较强的氧化作用,能明显降低G6PD缺乏者红细胞GSH水平,升高MetHb水平。葛根素仅降低G6PD缺乏者红细胞GSH水平,具有较弱的氧化作用。芦丁对G6PD缺乏者红细胞GSH和MetHb均无影响。较高浓度的槲皮素、芹菜素、桑黄素亦能使G6PD正常者MetHb水平升高。黄酮类化合物的氧化作用呈一定浓度依赖性,在中、高浓度时表现明显。结论:部分黄酮类化合物对G6PD缺乏者红细胞具有氧化作用,建议G6PD缺乏者慎用富含氧化性黄酮类化合物的中草药及其制剂。     

染料木素抗炎、镇痛、降尿酸作用实验研究

目的探讨染料木素是否具有抗炎镇痛作用,观察染料木素对正常小鼠血清尿酸水平的影响。方法选取BALB/c小鼠随机分为正常对照组、阳性对照组、染料木素3个剂量组,灌胃给药,连续7 d。采用热板法、扭体法、耳廓肿胀法,观察染料木素的镇痛抗炎作用,采用磷钨酸法测定小鼠血清尿酸水平。结果①染料木素对二甲苯致小鼠耳廓肿胀有明显的抑制作用,染料木素3个剂量组与正常对照组比较差异均具有统计学意义(P<0.01);②热板法实验中,染料木素能提高小鼠对热刺激的痛阈值,其中染料木素中、高剂量组与正常对照组比较具有统计学意义(P<0.01);③扭体法实验中,染料木素与正常对照组比较能显著减少扭体次数,表明染料木素具有一定的镇痛作用,3个剂量组与正常对照组比较差异均具有统计学意义(P<0.01);④染料木素中、高剂量组明显降低正常小鼠血清尿酸水平(P<0.01)。结论染料木素具有一定的镇痛抗炎作用,同时具有降低正常小鼠血清尿酸水平的作用。     

白杨素Mannich碱衍生物的合成及抗高尿酸血症活性

目的设计并合成新型具有抗高尿酸活性的白杨素Mannich碱衍生物。方法以天然产物白杨素为起始原料,与不同含氟有机物进行胺甲基化反应,合成系列白杨素Mannich碱衍生物。采用氯化硝基四氮唑蓝比色法测定目标化合物在体外对黄嘌呤氧化酶的抑制活性,并研究其在昆明种小鼠的体内抗高尿酸活性。结果与结论合成了10个未见文献报道的新化合物,目标化合物的结构经核磁共振氢谱和碳谱、电子轰击质谱(EI-MS)确证。体外活性实验显示,大多数含氟白杨素衍生物都具有较好的黄嘌呤氧化酶抑制作用,且体内抗高尿酸作用显著,在40 mg·kg~(-1)剂量时白杨素衍生物1a、1b、1c、1e、1f、1i和1j抗高尿酸效果最好,可使昆明种小鼠的血清尿酸值接近正常水平。     

尿酸对小鼠和鹌鹑脂质代谢的影响

目的:探讨高尿酸血症与高脂血症之间的相互关系。方法:应用不同动物模型诱导高尿酸血症或高脂血症,测定血液尿酸、甘油三酯、丙二醛浓度以及黄嘌呤氧化酶和脂肪酶活性,阐明尿酸对代谢性疾病的影响。结果:尿酸负荷显著升高小鼠血尿酸水平,尤以糖尿病小鼠尿酸升高更突出;脂负荷升高尿酸水平,同时进一步加重过氧化脂质的生成。尿酸负荷刺激糖尿病小鼠黄嘌呤氧化酶的活性升高,脂负荷对正常以及糖尿病小鼠黄嘌呤氧化酶均有刺激作用。尿酸负荷明显升高鹌鹑血清尿酸,脂负荷对血清尿酸、甘油三酯升高和过氧化脂质的形成均有明显的促进作用。与脂负荷相似,尿酸负荷明显增强血清脂肪酶的活性。结论:尿酸代谢紊乱是脂代谢失调的重要调节因素。     

金线莲提取物对黄嘌呤氧化酶活性及高尿酸血症小鼠的影响

目的 研究金线莲提取物体外抑制黄嘌呤氧化酶活性的作用和体内降尿酸的作用.方法 用黄嘌呤氧化酶(XOD)试剂盒测定不同浓度金线莲乙醇提取物和水提取物对黄嘌呤氧化酶活性的抑制作用;采用小鼠高尿酸血症模型研究了金线莲水提物对尿酸和肌酐水平的影响.结果 金线莲水提物对黄嘌呤氧化酶(XOD)具有较强的抑制作用,金线莲水提物低、高剂量组均显著降低血清尿酸水平(P<0.01)和血清肌酐水平(WTBXP<0.01).结论 金线莲水提物对小鼠高尿酸血症模型具有一定的治疗作用.     

芦丁与黄嘌呤氧化酶相互作用的电化学／紫外光谱性质研究

芦丁又名芸香苷,是一种从植物中提取的黄酮类化合物,具有抗炎、抗氧化、抗菌、抗癌和降血压等作用。大部分黄酮化合物都对黄嘌呤氧化酶有良好的抑制活性,但是由于黄酮化合物的结构差异．其性质也有很大不同。本文采用了电化学和紫外光谱法研究了芦丁对黄嘌呤氧化酶活性的抑制作用,结果发现芦丁对黄嘌呤氧化酶的活性基本没有抑制能力。     

Effects of Genistein, Apigenin, Quercetin, Rutin and Astilbin on serum uric acid levels and xanthine oxidase activities in normal and hyperuricemic mice

Flavonoids are widely found in plants and many of them possess biological and pharmacological activities. In the present study, we assessed the effects of the flavonoids Genistein, Apigenin, Quercetin, Rutin and Astilbin on xanthine oxidase (XO) activities in vitro, and in serum and the liver. The effects of the flavonoids on serum uric acid levels were also measured in vivo. In vitro studies indicated that the flavonoids tested did not significantly affect XO activity. However, significant increases and decreases in XO activities were observed in vivo. Moreover, serum XO activity was correlated with serum uric acid levels, while no correlation was observed for liver XO activity. The present study showed that serum uric acid levels in mice treated with the flavonoids tested here are higher than control levels. Therefore, the flavonoids tested here are not candidates for replacing Allopurinol as a treatment to reduce serum uric acid levels.     

Hypouricemic action of selected flavonoids in mice: structure-activity relationships

Hyperuricemia and gout appear to be rapidly increasing worldwide and frequently cause symptoms of metabolic syndrome. Dietary flavonoids have their potential beneficial effects on human health. In the present study, 15 flavonoids (quercetin, morin, myricetin, kaempferol, icariin, apigenin, luteolin, baicalin, silibinin, naringenin, formonoetin, genistein, puerarin, daidzin and naringin dihydrochalcone) were selected to investigate for their hypouricemic action in mice. Oral administration of quercetin, morin, myricetin, kaempferol, apigenin and puerarin at 50 and 100 mg/kg for 3 d was able to elicit hypouricemic actions in hyperuricemic mice induced by potassium oxonate. Luteolin, formonoetin and naringenin showed the significant effects only at 100 mg/kg. Quercetin, puerarin, myricetin, morin and kaempferol significantly reduced liver uric acid level in hyperuricemic animals. In addition, quercetin, morin, myricetin, kaempferol and puerarin exhibited significant inhibition on the liver xanthine oxidase (XOD) activities. It seems to be likely that these flavonoids reduce serum urate levels by mainly inhibiting XOD activity. However, the hypouricemic effect of apigenin observed seemed not to parallel with the changes in liver uric acid level and liver XOD activity, implying that apigenin might act via other mechanisms apart from inhibiting enzyme activity simply. Analysis of the chemical structure showed that a planar structure with the hydroxyl groups played a crucial role in hypouricemic activity of flavonoids. The exact mechanism of the hypouricemic action of flavonoids in vivo should be investigated in the future.     

Hypouricemic effect of the methanol extract from Prunus mume fruit in mice

Context: The fruit of the Prunus mume Sieb. et Zucc (Rosaceae) is used as a health food or medicinal material in traditional herb medicine for a long time in Eastern Asian countries.

Objective: Our present study investigated the hypouricemic effect of the methanol extract from P. mume fruit (MPMF) in mice with potassium oxonate-induced hyperuremia.

Materials and methods: Effect of MPMF (35, 70 and 140 mg/kg, p.o.) administrated for 7 days on the serum, liver, urinary uric acid levels and liver xanthine oxidase (XO) activity were assessed in mice.

Results: Hyperuricemic mice induced by potassium oxonate demonstrated an elevation in serum and liver uric acid levels (11.0 mg/dL and 0.52 mg/g tissue) and a reduction in urinary uric acid levels (49.9 mg/dL). Oral administration of 140 mg/kg MPMF for 7 days reversed the abnormalities in serum, liver and urinary uric acid levels (7.1 mg/dL, 0.37 mg/g tissue and 69.7 mg/dL, respectively). In addition, 70 and 140 mg/kg MPMF (3.1 and 2.9 nmol/min per mg protein) inhibited liver XO activity compared with hyperuricemic mice (3.9 nmol/min per mg protein).

Discussion and conclusion: The results indicated that the beneficial hypouricaemic effect of MPMF may be mediated, at least in part, by inhibiting XO activity in the liver. Our study suggests that P. mume and its extracts may have a considerable potential for development as an anti-gout agent for clinical application.     

尿酸在非酒精性脂肪性肝病形成的作用

非酒精性脂肪性肝病（nonalcoholic fatty liver disease, NAFLD）作为世界上最常见的慢性肝病之一,一直是研究的热点。NAFLD与肥胖及相关代谢紊乱密切相关。高尿酸血症或高血清尿酸水平是发生在肥胖者身上常见的代谢异常。流行病学研究证实了血清尿酸水平与非酒精性脂肪肝显著相关,而黄嘌呤氧化酶（xanthine oxidase, XO）是控制尿酸合成的关键酶。本文着重对尿酸及控制其合成的限速酶XO在NAFLD形成中的作用进行综述;阐述了尿酸与代谢综合症（metabolic syndrome, MS）相关疾病之间的关系,如胰岛素抵抗、糖尿病和高血脂;最后介绍了XO抑制剂在各种疾病治疗中的应用。     

Anti-oxidative assays as markers for anti-inflammatory activity of flavonoids

The complexity of in vitro anti-inflammatory assays, the cost and time consumed, and the necessary skills can be a hurdle to apply to promising compounds in a high throughput setting. In this study, several antioxidative assays i.e. DPPH, ABTS, ORAC and xanthine oxidase (XO) were used to examine the antioxidative activity of three sub groups of flavonoids: (i) flavonol: quercetin, myricetin, (ii) flavanone: eriodictyol, naringenin (iii) flavone: luteolin, apigenin. A range of flavonoid concentrations was tested for their antioxidative activities and were found to be dose-dependent. However, the flavonoid concentrations over 50 ppm were found to be toxic to the THP-1 monocytes. Therefore, 10, 20 and 50 ppm of flavonoid concentrations were tested for their anti-inflammatory activity in lipopolysaccharide (LPS)-stimulated THP-1 monocytes. Expression of inflammatory genes, IL-1β, IL-6, IL-8, IL-10 and TNF-α was found to be sequentially decreased when flavonoid concentration increased. Principle component analysis (PCA) was used to investigate the relationship between the data sets of antioxidative assays and the expression of inflammatory genes. The results showed that DPPH, ABTS and ORAC assays have an opposite correlation with the reduction of inflammatory genes. Pearson correlation exhibited a relationship between the ABTS assay and the expression of three out of five analyzed genes; IL-1β, IL-6 and IL-8. Our findings indicate that ABTS assay can potentially be an assay marker for anti-inflammatory activity of flavonoids.     

Transport of active flavonoids,based on cytotoxicity and lipophilicity: An evaluation using the blood–brain barrier cell and Caco-2 cell models

This in vitro study aims to evaluate and compare transmembrane transport of eight cardio-cerebrovascular protection flavonoids including puerarin, rutin, hesperidin, quercetin, genistein, kaempferol, apigenin and isoliquiritigenin via the rat blood–brain barrier cell and Caco-2 cell monolayer models, based on the data of cytotoxicity and lipophilicity. The cytotoxicity of the flavonoids to rat brain microvessel endothelial cell was determined by the MTT assay. The apparent permeability coefficients (P_app) of the flavonoids were calculated from the unilateral transport assays in Transwell system with simultaneous determination using a high performance liquid chromatography. The results showed that the cytotoxicity and oil–water partition coefficient of the flavonoids modified by the number and position of the glycoside and hydroxyl group were the key determinant for the transmembrane transport. The P_app values of the flavonoids reduced adversely when the numbers of glycoside and hydroxyl groups of the flavonoids increased accordingly. The tested flavonoids exhibited time-dependent P_app values in these models. The efflux mechanism related with P-glycoprotein also existed with the polar flavonoids; verapamil could enhance the permeation of rutin and quercetin via inhibition of P-glycoprotein. We propose that genistein and isoliquiritigenin with the permeation priority in vitro Caco-2 and BBB cell model could be better as the drug candidates for cardio-cerebral vascular protection. These findings provided important information for establishing the transport relationship for the flavonoid compounds and evaluating the potential oral bioavailability and brain distribution of the flavonoids.     

Prevention of cellular ROS damage by isovitexin and related flavonoids

The antioxidant properties of isovitexin and related flavonoids were studied. Isovitexin inhibited xanthine oxidase with an IC50 value of = 15.2 microM. The flavonoid analogues, apigenin, kaempferol, quercetin, myricetin, and genistein also inhibited xanthine oxidase with IC50 values of 0.58, 2.18, 1.09, 9.90, and 4.83 microM, respectively. Isovitexin protected DNA from the Fenton reaction-induced breakage in a dose-dependent manner with an IC50 value of 9.52 microM. Isovitexin also protected HL-60 cells from the ROS damage induced by the xanthine/xanthine oxidase reaction. Isovitexin exhibited the lowest cytotoxicity toward HL-60 cells (LD50 >400 microM) compared to the other flavonoids examined. In addition, excess hydrogen peroxide induced by cadmium in A2780 ovarian cells was significantly suppressed by isovitexin. These results suggest that isovitexin in rice may protect cells from oxidative stress.     

Flavonoids are scavengers of superoxide anions

Seven flavonoids and three non-flavonoid antioxidants, i.e. butylated hydroxyanisole, chlorpromazine and BW 755 C, were studied as potential scavengers of oxygen free radicals. Superoxide anions were generated enzymatically in a xanthine-xanthine oxidase system and non-enzymatically in a phenazine methosulphate-NADH system, and assayed by reduction of nitro blue tetrazolium. The generation of malonaldehyde (MDA) by the ascorbate-stimulated air-oxidised boiled rat liver microsomes was considered as an index of the non-enzymatic formation of hydroxyl radicals. Flavonoids but not non-flavonoid antioxidants lowered the concentration of detectable superoxide anions in both enzymic and non-enzymic systems which generated these SOD-sensitive radicals. The most effective inhibitors of superoxide anions were quercetin, myricetin and rutin. Four out of seven investigated flavonoids seemed also to suppress the activity of xanthine oxidase as measured by a decrease in uric acid biosynthesis. All ten investigated compounds inhibited the MDA formation by rat liver microsomes. Non-flavonoid antioxidants were more potent MDA inhibitors than flavonoids. It is concluded that antioxidant properties of flavonoids are effected mainly via scavenging of superoxide anions whereas non-flavonoid antioxidants act on further links of free radical chain reactions, most likely by scavenging of hydroxyl radicals.     

Photoproducts of indomethacin exhibit decreased hydroxyl radical scavenging and xanthine oxidase inhibition activities

Indomethacin (IN) is a widely used nonsteroidal anti-inflammatory drug. In this study, four photoproducts of IN (IN1–IN4) were produced and isolated from photoirradiated IN. This study investigated the abilities of IN and its photoproducts to scavenge hydroxyl radicals and inhibit xanthine oxidase (XO). The hydroxyl radical-scavenging activity was measured in vitro by electron spin resonance spectrometry using 5,5-dimethyl-1-pyrroline-N-oxide as a spin trapping agent. Enzyme activity was measured by continuous monitoring of uric acid formation, using xanthine as a substrate. The results showed that, among all the related products, IN has the strongest hydroxyl radical-scavenging (IC₅₀ = 65 μM) and XO inhibitory (IC₅₀ = 86 μM) effects. To further understand the stereochemistry of the reactions between these IN derivatives and XO, we performed computer-aided molecular modeling. IN was the most potent inhibitor with the most favorable interaction in the reactive site. Various photoproducts exhibited affinity toward XO as a result of the absence of hydrogen bonding with molybdopterin domain.